FROMLIST: [PATCH v5 09/12] arm: vdso: move vgettimeofday.c to lib/vdso/

(cherry pick from url https://patchwork.kernel.org/patch/10044497/)

Take an effort to recode the arm64 vdso code from assembler to C
previously submitted by Andrew Pinski <apinski@cavium.com>, rework
it for use in both arm and arm64, overlapping any optimizations
for each architecture. But instead of landing it in arm64, land the
result into lib/vdso and unify both implementations to simplify
future maintenance.

Declare arch/arm/vdso/vgettimeofday.c to be a candidate for a global
implementation of the vdso timer calls.  The hope is that new
architectures can take advantage of the current unification of
arm and arm64 implementations.

We urge future efforts to merge their implementations into the
global vgettimeofday.c file and thus provide functional parity.

Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Cc: James Morse <james.morse@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andy Gross <andy.gross@linaro.org>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Andrew Pinski <apinski@cavium.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Bug: 63737556
Bug: 20045882
Change-Id: If7da1d8144684d52ed9520a581e6023c623df931

2 files changed, 5 insertions, 342 deletions

diff --git a/arch/arm/vdso/compiler.h b/arch/arm/vdso/compiler.h
index c7751019246a..6fd88be2ff0e 100644
--- a/arch/arm/vdso/compiler.h
+++ b/arch/arm/vdso/compiler.h
@@ -34,6 +34,10 @@
 #error This code depends on AEABI system call conventions
 #endif
 
+#ifdef CONFIG_ARM_ARCH_TIMER
+#define ARCH_PROVIDES_TIMER
+#endif
+
 #define DEFINE_FALLBACK(name, type_arg1, name_arg1, type_arg2, name_arg2) \
 static notrace long name##_fallback(type_arg1 _##name_arg1,		  \
 				    type_arg2 _##name_arg2)		  \
diff --git a/arch/arm/vdso/vgettimeofday.c b/arch/arm/vdso/vgettimeofday.c
index 3005479efbe8..4b241fe60d17 100644
--- a/arch/arm/vdso/vgettimeofday.c
+++ b/arch/arm/vdso/vgettimeofday.c
@@ -1,344 +1,3 @@
-/*
- * Userspace implementations of gettimeofday() and friends.
- *
- * Copyright (C) 2017 Cavium, Inc.
- * Copyright (C) 2015 Mentor Graphics Corporation
- * Copyright (C) 2012 ARM Limited
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- * Author: Will Deacon <will.deacon@arm.com>
- * Rewriten from arch64 version into C by: Andrew Pinski <apinski@cavium.com>
- * Reworked and rebased over arm version by: Mark Salyzyn <salyzyn@android.com>
- */
-
-#include <asm/barrier.h>
-#include <linux/compiler.h>	/* for notrace				*/
-#include <linux/math64.h>	/* for __iter_div_u64_rem()		*/
-#include <uapi/linux/time.h>	/* for struct timespec			*/
-
 #include "compiler.h"
 #include "datapage.h"
-
-DEFINE_FALLBACK(gettimeofday, struct timeval *, tv, struct timezone *, tz)
-DEFINE_FALLBACK(clock_gettime, clockid_t, clock, struct timespec *, ts)
-DEFINE_FALLBACK(clock_getres, clockid_t, clock, struct timespec *, ts)
-
-static notrace u32 vdso_read_begin(const struct vdso_data *vd)
-{
-	u32 seq;
-
-	do {
-		seq = READ_ONCE(vd->tb_seq_count);
-
-		if ((seq & 1) == 0)
-			break;
-
-		cpu_relax();
-	} while (true);
-
-	smp_rmb(); /* Pairs with second smp_wmb in update_vsyscall */
-	return seq;
-}
-
-static notrace int vdso_read_retry(const struct vdso_data *vd, u32 start)
-{
-	u32 seq;
-
-	smp_rmb(); /* Pairs with first smp_wmb in update_vsyscall */
-	seq = READ_ONCE(vd->tb_seq_count);
-	return seq != start;
-}
-
-static notrace int do_realtime_coarse(const struct vdso_data *vd,
-				      struct timespec *ts)
-{
-	u32 seq;
-
-	do {
-		seq = vdso_read_begin(vd);
-
-		ts->tv_sec = vd->xtime_coarse_sec;
-		ts->tv_nsec = vd->xtime_coarse_nsec;
-
-	} while (vdso_read_retry(vd, seq));
-
-	return 0;
-}
-
-static notrace int do_monotonic_coarse(const struct vdso_data *vd,
-				       struct timespec *ts)
-{
-	struct timespec tomono;
-	u32 seq;
-	u64 nsec;
-
-	do {
-		seq = vdso_read_begin(vd);
-
-		ts->tv_sec = vd->xtime_coarse_sec;
-		ts->tv_nsec = vd->xtime_coarse_nsec;
-
-		tomono.tv_sec = vd->wtm_clock_sec;
-		tomono.tv_nsec = vd->wtm_clock_nsec;
-
-	} while (vdso_read_retry(vd, seq));
-
-	ts->tv_sec += tomono.tv_sec;
-	/* open coding timespec_add_ns */
-	ts->tv_sec += __iter_div_u64_rem(ts->tv_nsec + tomono.tv_nsec,
-					 NSEC_PER_SEC, &nsec);
-	ts->tv_nsec = nsec;
-
-	return 0;
-}
-
-#ifdef CONFIG_ARM_ARCH_TIMER
-
-/*
- * Returns the clock delta, in nanoseconds left-shifted by the clock
- * shift.
- */
-static notrace u64 get_clock_shifted_nsec(const u64 cycle_last,
-					  const u32 mult,
-					  const u64 mask)
-{
-	u64 res;
-
-	/* Read the virtual counter. */
-	res = arch_vdso_read_counter();
-
-	res = res - cycle_last;
-
-	res &= mask;
-	return res * mult;
-}
-
-static notrace int do_realtime(const struct vdso_data *vd, struct timespec *ts)
-{
-	u32 seq, mult, shift;
-	u64 nsec, cycle_last;
-#ifdef ARCH_CLOCK_FIXED_MASK
-	static const u64 mask = ARCH_CLOCK_FIXED_MASK;
-#else
-	u64 mask;
-#endif
-	vdso_xtime_clock_sec_t sec;
-
-	do {
-		seq = vdso_read_begin(vd);
-
-		if (vd->use_syscall)
-			return -1;
-
-		cycle_last = vd->cs_cycle_last;
-
-		mult = vd->cs_mono_mult;
-		shift = vd->cs_shift;
-#ifndef ARCH_CLOCK_FIXED_MASK
-		mask = vd->cs_mask;
-#endif
-
-		sec = vd->xtime_clock_sec;
-		nsec = vd->xtime_clock_snsec;
-
-	} while (unlikely(vdso_read_retry(vd, seq)));
-
-	nsec += get_clock_shifted_nsec(cycle_last, mult, mask);
-	nsec >>= shift;
-	/* open coding timespec_add_ns to save a ts->tv_nsec = 0 */
-	ts->tv_sec = sec + __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec);
-	ts->tv_nsec = nsec;
-
-	return 0;
-}
-
-static notrace int do_monotonic(const struct vdso_data *vd, struct timespec *ts)
-{
-	u32 seq, mult, shift;
-	u64 nsec, cycle_last;
-#ifdef ARCH_CLOCK_FIXED_MASK
-	static const u64 mask = ARCH_CLOCK_FIXED_MASK;
-#else
-	u64 mask;
-#endif
-	vdso_wtm_clock_nsec_t wtm_nsec;
-	__kernel_time_t sec;
-
-	do {
-		seq = vdso_read_begin(vd);
-
-		if (vd->use_syscall)
-			return -1;
-
-		cycle_last = vd->cs_cycle_last;
-
-		mult = vd->cs_mono_mult;
-		shift = vd->cs_shift;
-#ifndef ARCH_CLOCK_FIXED_MASK
-		mask = vd->cs_mask;
-#endif
-
-		sec = vd->xtime_clock_sec;
-		nsec = vd->xtime_clock_snsec;
-
-		sec += vd->wtm_clock_sec;
-		wtm_nsec = vd->wtm_clock_nsec;
-
-	} while (unlikely(vdso_read_retry(vd, seq)));
-
-	nsec += get_clock_shifted_nsec(cycle_last, mult, mask);
-	nsec >>= shift;
-	nsec += wtm_nsec;
-	/* open coding timespec_add_ns to save a ts->tv_nsec = 0 */
-	ts->tv_sec = sec + __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec);
-	ts->tv_nsec = nsec;
-
-	return 0;
-}
-
-static notrace int do_monotonic_raw(const struct vdso_data *vd,
-				    struct timespec *ts)
-{
-	u32 seq, mult, shift;
-	u64 nsec, cycle_last;
-#ifdef ARCH_CLOCK_FIXED_MASK
-	static const u64 mask = ARCH_CLOCK_FIXED_MASK;
-#else
-	u64 mask;
-#endif
-	vdso_raw_time_sec_t sec;
-
-	do {
-		seq = vdso_read_begin(vd);
-
-		if (vd->use_syscall)
-			return -1;
-
-		cycle_last = vd->cs_cycle_last;
-
-		mult = vd->cs_raw_mult;
-		shift = vd->cs_shift;
-#ifndef ARCH_CLOCK_FIXED_MASK
-		mask = vd->cs_mask;
-#endif
-
-		sec = vd->raw_time_sec;
-		nsec = vd->raw_time_nsec;
-
-	} while (unlikely(vdso_read_retry(vd, seq)));
-
-	nsec += get_clock_shifted_nsec(cycle_last, mult, mask);
-	nsec >>= shift;
-	/* open coding timespec_add_ns to save a ts->tv_nsec = 0 */
-	ts->tv_sec = sec + __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec);
-	ts->tv_nsec = nsec;
-
-	return 0;
-}
-
-#else /* CONFIG_ARM_ARCH_TIMER */
-
-static notrace int do_realtime(const struct vdso_data *vd, struct timespec *ts)
-{
-	return -1;
-}
-
-static notrace int do_monotonic(const struct vdso_data *vd, struct timespec *ts)
-{
-	return -1;
-}
-
-static notrace int do_monotonic_raw(const struct vdso_data *vd,
-				    struct timespec *ts)
-{
-	return -1;
-}
-
-#endif /* CONFIG_ARM_ARCH_TIMER */
-
-notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
-{
-	const struct vdso_data *vd = __get_datapage();
-
-	switch (clock) {
-	case CLOCK_REALTIME_COARSE:
-		do_realtime_coarse(vd, ts);
-		break;
-	case CLOCK_MONOTONIC_COARSE:
-		do_monotonic_coarse(vd, ts);
-		break;
-	case CLOCK_REALTIME:
-		if (do_realtime(vd, ts))
-			goto fallback;
-		break;
-	case CLOCK_MONOTONIC:
-		if (do_monotonic(vd, ts))
-			goto fallback;
-		break;
-	case CLOCK_MONOTONIC_RAW:
-		if (do_monotonic_raw(vd, ts))
-			goto fallback;
-		break;
-	default:
-		goto fallback;
-	}
-
-	return 0;
-fallback:
-	return clock_gettime_fallback(clock, ts);
-}
-
-notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
-{
-	const struct vdso_data *vd = __get_datapage();
-
-	if (likely(tv != NULL)) {
-		struct timespec ts;
-
-		if (do_realtime(vd, &ts))
-			return gettimeofday_fallback(tv, tz);
-
-		tv->tv_sec = ts.tv_sec;
-		tv->tv_usec = ts.tv_nsec / 1000;
-	}
-
-	if (unlikely(tz != NULL)) {
-		tz->tz_minuteswest = vd->tz_minuteswest;
-		tz->tz_dsttime = vd->tz_dsttime;
-	}
-
-	return 0;
-}
-
-int __vdso_clock_getres(clockid_t clock, struct timespec *res)
-{
-	long nsec;
-
-	if (clock == CLOCK_REALTIME ||
-	    clock == CLOCK_MONOTONIC ||
-	    clock == CLOCK_MONOTONIC_RAW)
-		nsec = MONOTONIC_RES_NSEC;
-	else if (clock == CLOCK_REALTIME_COARSE ||
-		 clock == CLOCK_MONOTONIC_COARSE)
-		nsec = LOW_RES_NSEC;
-	else
-		return clock_getres_fallback(clock, res);
-
-	if (likely(res != NULL)) {
-		res->tv_sec = 0;
-		res->tv_nsec = nsec;
-	}
-
-	return 0;
-}
+#include "../../../lib/vdso/vgettimeofday.c"